Ever wonder how the U.S. interstates that you drive on every day got their name? This quick and informative video breaks down the “interstate’s forgotten code” to show viewers how the roadways were built and named.

A video created by YouTuber CGP Grey walks you through the U.S. interstate numbering system, detailing how east-west major interstates are numbered ending in zero and north-south major interstates are numbered ending with 5. The video also goes through naming rules for interstate mediums and minor interstates, as well as some interesting exceptions to the rules.

Check out the video below!

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